Nucleic Acids Research, 1984, Vol. 12, No. 19 7503-7515
© 1984
MOLECULAR BIOLOGY |
Inhibition of polyoma DNA synthesis by base pair substitutions at the replication origin
,*Medical Nobel Institute, Department of Biochemistry, Karolinska Institute Box 60400, S-10401 Stockholm, Sweden
*To whom correspondence should be addressed
Received July 30, 1984. Revised August 30, 1984. Accepted August 30, 1984.
The effect of base pair substitutions on the function of the polyoma virus origin of DNA replication was studied. The mutations were all C-G to T-A transitions, Induced by bisulfite treatment of recombinant DNA molecules. The mutagenesis was directed to short single-stranded gaps 1n duplex DNA, or to loops In heteroduplex molecules. Modification of a 34 base pair sequence of dyad symmetry led to cis-acting inhibition of viral DNA synthesis, ranging from slight defects to total inactivation. One of the mutants was temperature sensitive. Mutants with base changes in an adjacent DNA segment, including an 18 base pair long purine-pyrimidine tract, had similar, but less severe, deficiences. In contrast to the effect of mutations in the homologous region of the simian virus 40 genome, there was no strict relationship between mutation of the putative large T-antigen-binding base sequence GPuGGC and defective viral DNA synthesis.
+Present address: Department of Clinical Genetics, Karolinska Institute
Present address: Department of Medical Vitology, Uppsala University, Box 584, S-75123 Uppsala, Sweden.